A successful SEO campaign includes a Google+ strategy, yet many companies are still not thinking about Google+ as such a crucial aspect for SEO. Your typical social media benefits are obvious—on-site engagement, targeted messages, connections and referrals, etc.
The short explanation is this: If someone you are connected with on Google+ either writes an article or +1s an article, that article is more likely to show up on your specific SERP because a person you trust found that article useful. If you’re a company, you’re going to want to be that search result.
Via Ivo Nový